This invention relates to security systems, in particular those that utilize sensors or magnetic contacts to determine whether a protected zone has been violated. Typically, more than one sensor will be attached and able to communicate with a single, microprocessor-driven programmable alarm panel. Standard panels usually control up to eight distinct zones on a closed loop system. Furthermore, each zone can contain more than one sensor/contact. In either case, the alarm panel not only provides power to the closed loop in which the sensors and contacts are attached but also provides status information to sensors on the loop on the "status line" of each sensor.
In the prior art, the status of an alarm panel can be ARMED or DISARMED. As the names suggest, the system provides intruder monitoring in the zone during the ARMED condition whereas in a DISARMED condition the system is inactive. Additionally, an alarm system can be programmed from the alarm panel to bypass certain zones. For instance, the system can be programmed to monitor zones on a second floor of a location but ignore signals from the first floor of the location where authorized personnel may be present. In such an example, the system bypasses first floor zones by ignoring signals received from sensors and contacts in the zones of the first floor. However, the overall status of the system is provided to every sensor in the security loop as either being ARMED or DISARMED. In other words, the sensors and contacts on the main floor are unaware that they have been individually bypassed.
The "intelligent" sensors utilized in security systems today are sophisticated enough to learn information about their individual zones to adjust their signal processing. For instance, a sensor can be made more stable to eliminate false alarms which might otherwise be caused by a heating duct, ceiling fan, a pet, or the like. An example of such a self-adjusting system is described in U.S. Pat. No. 5,331,308 entitled AUTOMATICALLY ADJUSTABLE AND SELF-TESTING DUAL TECHNOLOGY INTRUSION DETECTION SYSTEM FOR MINIMIZING FALSE ALARMS. Some of the most effective "learning" in a zone can be conducted during a period in which that zone is bypassed although the system itself is ARMED. Regrettably, no means exist for a bypassed zone to know it has a bypass status when the system itself is ARMED.
One disadvantage of the inability of individual sensors to recognize whether they are active or bypassed is that it prevents such sensors from effectively performing the dual function of being both an intruder detector and a high sensitivity occupancy sensor utilizing a single output. Following the example described above wherein second floor zones are active and first floor zones are bypassed, it would be highly advantageous to use the sensors on the first floor to control lights, etc. Regrettably, since the system is ARMED, the individual sensors on the first floor are established at a very stable sensitivity setting in order to avoid false alarms. However, since such first floor sensors are inactive (or bypassed), false alarms are not of any concern. This stable setting under such circumstances prevents effective use of such sensors as providing high sensitivity occupancy detection which is utilized in home automation systems.
In the most advanced conventional alarm systems, sensor settings have been established to account for pets in order to avoid false alarms. For example, the spaces closest to the ground in a protected zone can be set to be more stable than higher spaces. Obviously, while such processing greatly reduces false alarms caused by the presence of pets, it also increases the likelihood of the failure to "catch" an intruder in the protected zone. Thus, such settings, which account for the presence of pets, should only be made when the pets are indeed in the premises. Typically, the decision to set a sensor as a "pet" or "no pet" zone is made when the installer first establishes the alarm system. However, often people who have pets give them up and people who originally did not have pets obtain one. In such scenarios, the only way to reset the "pet" setting is at the sensor. It would be highly advantageous if the alarm control panel could provide "pet" settings and "no pet" settings to individual sensors as desired. Such a feature would also permit pet owners to house their pets in different zones as desired.
Another shortcoming in the prior art systems wherein individual zones are unaware whether they are bypassed or active relates to customer satisfaction. Many sensors include an indicator light to visually illustrate "catch." Customers often become dismayed and contact their alarm service provider when they notice that a sensor in a bypassed zone does not immediately indicate their presence in that zone. If a particular bypassed zone could recognize that it was being bypassed, it could be established at an extremely high sensitivity so that it would more promptly note the presence of the customer in the bypassed zone. However, since the bypassed zone is unaware it is being bypassed, it is typically set at a more stable setting to eliminate false alarms. While the sensor in the bypassed zone is indeed functioning as programmed, the customer believes it is not.
Presently the only effective individualized communication between a panel and individual sensors in a system is the ability of the panel to inject a signal on the loop to determine if each zone is present. For instance, in U.S. Pat. No. 4,754,262 entitled MULTIPLEXED ALARM SYSTEM a synchronized signal is transmitted to all transponders. Each transponder number has associated with it a unique delay time in which a response signal would be received based on the injected signal. The absence of such a response signal would signify a "trouble" condition with that sensor. At most, such systems simply identify each functioning zone. However, each zone is not provided information as to whether it is active or being bypassed.
It is, therefore, a primary object of the present invention to provide a new and improved panel-controlled sensor in an intruder detection system.
It is another object of the present invention to provide a new and improved panel-controlled sensor in an intruder detection system which provides enhanced reliability.
It is yet a further object of the present invention to provide a new and improved panel-controlled sensor in an intruder detection system wherein the system has fewer false alarms.
It is yet another object of the present invention to provide a new and improved panel-controlled sensor in an intruder detection system wherein end user satisfaction is achieved by more readily indicating intruder "catch."
It is still another object of the present invention to provide a new and improved panel-controlled sensor in an intruder detection system which permits additional features, such as the detection of various trouble conditions at each sensor, at no additional cost.
It is yet an additional object of the present invention to provide a new and improved panel-controlled sensor in an intruder detection system that allows a panel to set each sensor in the system to a "pet" setting or a "no petting" setting.
It is a further object of the present invention to provide a new and improved panel-controlled sensor in an intruder detection system wherein each sensor in the system can more effectively perform the second function of being a high sensitivity occupancy sensor when it is bypassed.
It is a further object of the present invention to provide a new and improved panel-controlled sensor in an intrusion detection system which allows each sensor to determine whether it is active or bypassed.
It is still another object of the present invention to provide a new and improved panel-controlled sensor in an intrusion detection system wherein the aforementioned advantages are achieved through a standard four-wire configuration.